Cooling of neutron stars - Effects of the finite time scale of thermal conduction

Abstract

Evolutionary sequences are calculated for a nonrotating, nonmagnetic neutron star using the best physical input currently available and a fully general relativistic stellar evolution code. Effects of equations of state, mass, and uncertainty in theories of superfluidity are taken into account. The calculations are confined to 'standard' cooling, where the absence of any 'exotic' cooling agents such as charged pion condensates and quarks is assumed. Among various improvements applied in the calculations, by far the most important is the effect of the finite time scale of thermal conduction. For instance, it is found that for a neutron star model of intermediate softness it would take nearly 1000 yr to reach the isothermal state. This time scale would be considerably longer for stiffer models, for instance, nearly 100,000 yr for a PS model.